Why do this problem?
Moving through each of the challenges gives an opportunity for children to work investigatively. Children's curiosity will take them to many different places as they work on this challenge. This task is a good example that offers both a 'low threshold' starting point and at the same time offers a 'high ceiling' for those pupils who are inclined to explore much further.
It will probably be best to have the whole group/class with you, extending together the spiral to 144.
Then set challenge 2 by starting them off to ensure that as well as adding 111, 73 and 43 they'll have to add up the next three as 73, 43 and 21 (not just 21, 7, and 1), so that they have to produce ten totals altogether. (You may decide not to tell them that, but instead have some feedback from them when they have completed challenge 2).
How are you getting your totals of three?
What are you doing to try to get your totals to end in a 2 (or an 8)?
Tell me what you are doing.
Exploring the ten totals of threes, what can they find out?
What about extending the spiral past 144?
Some pupils may need a calculator to help with the many additions that they want to carry out.